Turtle in a Tank Domesticating Turtles, the right way! Pet Attack

Turtle in a Tank Domesticating Turtles, the right way! Pet Attack

Turtles are diapsids of the particular order Testudines (or Chelonii) characterized by a special bony or cartilaginous shell developed from their ribs plus acting as a shield. "Turtle" may refer to the order as a whole (American English) or to fresh-water and sea-dwelling testudines (British English). The particular order Testudines includes both extant (living) and wiped out species. The earliest known members of this team date from 220 mil years ago, making turtles one of the oldest reptile groups and a more ancient group compared to snakes or crocodilians. Of the 356 known types alive today, some are highly endangered.

Turtles are usually ectotherms—animals commonly called cold-blooded—meaning that their internal temp varies according to the particular ambient environment. However, since of their high metabolic rate, leatherback sea turtles have a body temperature that is noticeably increased than that of the particular surrounding water. Turtles are usually classified as amniotes, along with other reptiles, parrots, and mammals. Like additional amniotes, turtles breathe air flow and do not lay down eggs underwater, although numerous species live in or around water. The study of turtles is called cheloniology, after the Greek term for turtle. It is also sometimes called testudinology, after the Latin title for turtles.

Differences can be found in usage of the particular common terms turtle, tortoise, and terrapin, depending on the variety of English being utilized. These terms are common names and don't reflect exact biological or taxonomic variations.

Turtle may either relate to the order as a whole, or to particular turtles that make up a form taxon that is not monophyletic, or may be restricted to only aquatic species. Tortoise usually pertains to any land-dwelling, non-swimming chelonian. Terrapin can be used to describe several species of small, edible, hard-shell turtles, typically those found in brackish waters.

In North America, all chelonians are usually commonly called turtles. Tortoise is used only within reference to fully terrestrial turtles or, more narrowly, only those members of Testudinidae, the family of modern property tortoises. Terrapin may recommend to small semi-aquatic turtles that live in fresh and brackish water, specifically the diamondback terrapin (Malaclemys terrapin). Although the users from the genus Terrapene live mostly on land, these people are known as box turtles rather than tortoises. The American Society of Ichthyologists and Herpetologists uses "turtle" to describe all species of the order Testudines, regardless of whether they are land-dwelling or sea-dwelling, and uses "tortoise" like a more specific expression for slow-moving terrestrial species.

In the United Kingdom, the word turtle is utilized for water-dwelling species, including ones known in the particular US as terrapins, although not for terrestrial species, which are known only as tortoises.

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Facts Discovery Sea Turtle Exploration

The word chelonian is popular among veterinarians, scientists, plus conservationists working with these types of animals like a catch-all name for any member of the superorder Chelonia, including just about all turtles living and extinct, as well as their own immediate ancestors. Chelonia is usually based on the Ancient greek word for turtles, χελώνη chelone; Greek χέλυς chelys "tortoise" is also utilized in the formation of medical names of chelonians. Testudines, on the other hands, is based on the Latin word for tortoise, testudo. Terrapin comes through an Algonquian word with regard to turtle.

Some languages do not have this variation, as all of these types of are referred to by the particular same name. For example , in Spanish, the word tortuga is used for turtles, tortoises, and terrapins. A sea-dwelling turtle is tortuga marina, a freshwater types tortuga de río, and a tortoise tortuga terrestre.

The largest living chelonian is the leatherback sea turtle (Dermochelys coriacea), which usually reaches a shell length of 200 cm (6. six ft) and can reach a weight of more than 900 kg (2, 1000 lb). Freshwater turtles are generally smaller, but with the largest species, the Asian softshell turtle Pelochelys cantorii, a few people have been reported upward to 200 cm (6. 6 ft). This dwarfs even the better-known alligator snapping turtle, the biggest chelonian in North The united states, which attains a covering length of up to 80 cm (2. 6 ft) and weighs because much as 113. four kg (250 lb).

Large tortoises of the genera Geochelone, Meiolania, and others were relatively widely distributed around the world into prehistoric periods, and therefore are known to possess existed in North plus South America, Australia, plus Africa. They became vanished at the same period as the appearance associated with man, and it will be assumed humans hunted all of them for food. The just surviving giant tortoises are usually on the Seychelles plus Galápagos Islands and may grow to over 130 cm (51 in) in duration, and weigh about three hundred kg (660 lb).

The particular largest ever chelonian has been Archelon ischyros, a Past due Cretaceous sea turtle identified to have been up to 4. 6 m (15 ft) long.

Glyptemys Wikipedia

The smallest turtle is the speckled padloper tortoise of Southern Africa. It measures simply no more than 8 centimeter (3. 1 in) long and weighs about a hundred and forty g (4. 9 oz). Two other species associated with small turtles are the particular American mud turtles and musk turtles that reside in an area that ranges from Canada in order to South America. The cover duration of many species within this group is less than 13 cm (5. 1 in) long.

Turtles are divided into two groups, according to how they retract their necks to their shells (something the our ancestors Proganochelys could not do). The mechanism of neck of the guitar retraction differs phylogenetically: the suborder Pleurodira retracts side to side aside, anterior to make girdles, while the suborder Cryptodira retracts straight back again, between shoulder girdles. These types of motions are largely due to the morphology and arrangement of cervical vertebrae. Of all recent turtles, the cervical column is made up of nine joints plus eight vertebrae, which are individually independent. Since these vertebrae are not fused and are rounded, the neck is more versatile, being able to bend in the backwards plus sideways directions. The major function and evolutionary implication of neck retraction will be thought to be for feeding rather than safety. Neck retraction and testing extension allows the turtle to achieve out further to capture prey while swimming. Neck expansion creates suction when the head is drive forward and the oropharynx is expanded, and this morphology suggests the retraction function is for feeding purposes as the suction helps catch prey. The particular protection the shell provides the head when it is retracted is therefore not the main function of retraction, thus is usually an exaptation. As with regard to the difference between the two methods of retraction, both Pleurodirans and Cryptodirans use the quick expansion of the neck like a method of predation, therefore the difference in retraction mechanism is just not due to a difference in ecological niche.

Head

Most turtles that spend most associated with their lives on land get their eyes looking down at objects in front of them. Some marine turtles, such as snapping turtles and soft-shelled turtles, have eyes closer in order to the top of the mind. These types of turtle may hide from predators in shallow water, where they lie entirely submerged except for their eyes plus nostrils. Near their eyes, sea turtles possess glands that produce salty tears that rid themselves of excess salt consumed from the water they consume.

Turtles have rigid beaks and use their jaws to cut and chew food. Instead of getting teeth, that they appear to have lost about 150-200 million years ago, the particular upper and lower teeth of the turtle are covered by horny side rails. Carnivorous turtles usually have knife-sharp ridges for slicing through their prey. Herbivorous turtles have serrated-edged ridges that help them cut through tough plants. These people use their tongues to swallow food, but unlike most reptiles, they cannot stick out their tongues in order to catch food.

ShellPrimary article: Turtle shellTop of the shell of the turtle is known as the carapace. The particular lower shell that encases the belly is called the plastron. The carapace and plastron are joined up with together on the turtle's sides by bony constructions called bridges. The inner layer of a turtle's shell is made upward of about 60 bones that include portions of the backbone and the particular ribs, meaning the turtle cannot crawl out of the shell. In most turtles, the outer layer from the shell is covered by horny scales called scutes which are part of its outer skin, or epidermis. Scutes comprise of the fibrous protein keratin that also makes up the scales of other lizards. These scutes overlap the particular seams between the shell bones and add strength to the shell. Some turtles do not possess horny scutes; regarding example, the leatherback sea turtle and the soft-shelled turtles have shells covered with leathery skin instead.

The shape of the covering gives helpful clues about how a turtle lives. Many tortoises have a large, dome-shaped shell that can make it difficult for predators to crush the cover between their jaws. One of the few conditions is the African pancake tortoise, which has the flat, flexible shell that will allows it to hide in rock crevices. Many aquatic turtles have flat, streamlined shells, which aid in swimming and diving. American snapping turtles and musk turtles have small, cross-shaped plastrons that give them more efficient leg movement for walking along the particular bottom of ponds plus streams. Another exception is usually the Belawan Turtle (Cirebon, West Java), that has sunken-back soft-shell.

The color of a turtle's shell may differ. Shells are commonly colored brown, black, or olive green. In some species, covers may have red, orange, yellow, or grey marks, often spots, lines, or irregular blotches. One of the most vibrant turtles is the eastern painted turtle, which contains a yellow plastron and a black or olive shell with red markings around the rim.

Tortoises, being land-based, have rather heavy shells. In comparison, aquatic and soft-shelled turtles have lighter shells that will help them avoid sinking in water and swim faster with more speed. These lighter shells possess large spaces called fontanelles between the shell bone fragments. The shells of leatherback sea turtles are extremely light because they lack scutes and contain many fontanelles.

It has been suggested by Jackson (2002) that will the turtle shell may function as pH barrier. To endure through anoxic conditions, such as winter periods trapped beneath glaciers or within anoxic dirt at the end of ponds, turtles utilize two general physiological mechanisms. In the situation of prolonged periods associated with anoxia, it has already been shown the turtle shell both releases carbonate buffers and uptakes lactic acid.

From the Shadow of the Tetons: Bucket list release baby sea turtles Visit to the Nuevo

Respiration Turtles

Respiration, for many amniotes, is achieved by the particular contraction and relaxation associated with specific muscle groups (i. electronic. intercostals, abdominal muscles, and/or a diaphragm) mounted on an inner rib-cage that can broaden or contract the entire body wall thus assisting airflow out and in of the lung area. The ribs of Chelonians, however, are fused with their carapace and exterior to their pelvic and pectoral girdles, a function unique among turtles. This particular rigid shell is not really capable of expansion, plus by rendering their rib-cage immobile, Testudines have got to evolve special modifications for respiration.

Turtle pulmonary ventilation occurs by using specific categories of abdominal muscle groups attached to their viscera and shell that pull the lungs ventrally during inspiration, where air is usually drawn in via a negative pressure gradient (Boyle's Law). In expiration, the particular contraction from the transversus abdominis is the driving force by propelling the viscera into the lungs and expelling air under good pressure. Conversely, the comforting and flattening of the particular oblique abdominis muscle drags the transversus back straight down which, once again, draws air back into the lung area. Important auxiliary muscles utilized for ventilatory processes are the pectoralis, which is utilized in conjunction with the transverse abdominis during inspiration, as well as the serratus, which movements with all the abdominal oblique associated expiration.

The lungs associated with Testudines are multi-chambered plus attached their entire duration throughout the carapace. The number of chambers can vary between taxa, though most commonly they have three lateral chambers, three medial chambers, and something terminal chamber. As mentioned earlier on, the act of particular abdominal muscles pulling lower the viscera (or pressing back up) is exactly what allows for respiration within turtles. Specifically, it is usually the turtles large liver organ that pulls or forces on the lungs. Ventral to the lungs, in the coelomic cavity, the liver organ of turtles is connected directly to the correct lung, and their stomach is directly attached to the left lung simply by the ventral mesopneumonium, which is attached to their liver organ by the ventral mesentery. When the liver is drawn down, inspiration begins. Assisting the lungs is the post-pulmonary septum, that is discovered in all Testudines, and is thought to prevent the lungs from collapsing.

turtles The Wild World of Zoobooks

Turtles Skin and molting

As pointed out above, the outer coating of the shell will be part of the epidermis; each scute (or plate) on the shell corresponds to a single revised scale. The remainder of the skin has much smaller scales, just like the pores and skin of other reptiles. Turtles do not molt their own skins all at as soon as as snakes do, yet continuously in small pieces. When turtles are held in aquaria, small linens of dead skin can be seen in the water (often appearing to be a thin piece of plastic) having been sloughed off when the particular animals deliberately rub themselves against some wood or even stone. Tortoises also drop skin, but dead epidermis is allowed to accumulate in to thick knobs and plates that provide protection to parts of the body outside the shell.

Simply by counting the rings shaped by the stack of smaller, older scutes on top of the larger, newer types, it is possible to estimate the age of a turtle, if one knows the number of scutes are produced in a year. This method is not very accurate, partly due to the fact growth rate is not really constant, but also since some of the scutes eventually fall away through the shell.

Turtles Braches

Terrestrial tortoises have short, sturdy feet. Tortoises are famous for moving slowly, simply because of their large, cumbersome shells, which limit stride length.

Skeleton associated with snapping turtle (Chelydra serpentina)

Amphibious turtles normally possess limbs similar to those of tortoises, except that the feet are webbed plus often have long claws. These turtles swim making use of all four feet in a way similar to the dog paddle, with the feet on the particular right and left side of the particular body alternately providing thrust. Large turtles tend to swim less than smaller sized ones, and the really big species, such because alligator snapping turtles, hardly swim at all, preferring to walk along the bottom associated with the river or lake. As well as webbed feet, turtles have extremely long claws, used to help them clamber onto riverbanks and floating records upon which they bask. Male turtles tend to have particularly long paws, and these seem to be utilized to stimulate the female while mating. While many turtles have webbed feet, some, like the pig-nosed turtle, have true flippers, along with the digits being fused into paddles and the claws being relatively small. These species swim in the same manner because sea turtles do (see below).

Sea turtles are almost entirely aquatic plus have flippers instead of feet. Sea turtles travel with the water, using the up-and-down motion of the particular front flippers to create drive; the back feet are not used for propulsion but may be used as rudders for steering. Compared with freshwater turtles, sea turtles possess very limited mobility upon land, and apart from the dash from the nest to the sea as hatchlings, man sea turtles normally never ever leave the sea. Women must come back onto land to lay ovum. They move very gradually and laboriously, dragging on their own forwards with their flippers.

Habits of Turtles

Senses of Turtles are thought to have exceptional night vision because of the unusually large quantity of rod cells within their retinas. Turtles possess color vision with a wealth of cone subtypes with sensitivities ranging from the near ultraviolet (UVA) to red. Some land turtles have very bad pursuit movement abilities, which are normally found just in predators that hunt quick-moving prey, but carnivorous turtles are able to move their heads quickly to snap.

Turtles Communication

The Arrau turtle has a sizable vocal repertoire.

Whilst typically thought of as mute, turtles make various sounds when communicating. Tortoises might be vocal when courting and mating. Various species of both freshwater plus sea turtles emit many types of calls, usually short and low frequency, from the time they are in the egg to when they are adults. These vocalizations may serve to create group cohesion when migrating.

Turtle Cleverness

See furthermore: Animal cognition

It provides been reported that wooden turtles are better compared to white rats at studying to navigate mazes. Situation studies exist of turtles playing. They are doing, however, possess a very low encephalization quotient (relative brain in order to body mass), and their hard shells enable these to live without fast reflexes or elaborate predator avoidance strategies. In the lab, turtles (Pseudemys nelsoni) may learn novel operant duties and also have demonstrated a long lasting memory of at minimum 7. 5 months.

Turtle Mating Strategies

An instance of mounting behavior within turtles

Turtles are recognized for displaying a wide variety of mating behaviors, nevertheless , they are not really known for forming pair-bonds or for being component of a social team. Once fertilization has occurred and an offspring offers been produced, neither mother or father will provide care with regard to the offspring once is actually hatched. Females generally outnumber males in various turtle species (such as Green turtles), and as a result, most men will take part in multiple copulation with multiple partners throughout their lifespan. However, because of to the sexual dimorphism present in most turtle species, males must create different courting strategies or even use alternate methods in order to gain access to a potential mate. Most terrestrial species have males that are bigger than females, and fighting between males often decides a hierarchical order in which the higher up the order an individual is, the better the chance is of the individual getting access to a potential mate. For most semi-aquatic species and bottom-walking aquatic species, combat occurs less often. Males belonging to semi-aquatic and bottom-walking species instead often make use of their larger size benefit to forcibly mate with a female. In fully marine species, males are frequently smaller than females and therefore they cannot use the same strategy as their semi-aquatic relatives, which relies on overwhelming the females with strength. Males in this class resort to using courtship displays in an try to gain mating accessibility to a female.

Battling Between Males Turtles

Saddle back Galapagos tortoise

Wood turtles is surely an example of a terrestrial species where the particular males have a hierarchical ranking system based upon dominance through fighting, plus it's shown that the males with the greatest rank and thus the particular most wins in arguements have the most children.

Galapagos tortoises are one more example of a species which has a hierarchical rank that is determined by dominance displays, and entry to food and mates is regulated by this dominance hierarchy. Two male saddle backs most usually compete for access to cactus trees, which is their particular source of food. The particular winner is the individual who stretches their neck of the guitar the highest, and that person gets access to the particular cactus tree, which can attract potential mates.

Pressure Mating Turtles

Male (left) plus female (right) radiated tortoise

The male scorpion mud turtle is an illustration of a bottom-walking marine species that depends on overpowering females with its bigger size as a mating strategy. The male approaches the female from the back, and often resorts in order to aggressive methods for example gnawing at the female's tail or even hind limbs, followed by a mounting behavior in which the male clasps the edges of her carapace with his forelimbs and hind limbs to hold the girl in position. The man follows this action by laterally waving his head and sometimes biting the female's head in a good attempt to get the girl to withdraw her go to her shell. This reveals her cloaca, and along with it exposed, the man can attempt copulation by trying to insert his holding tail.

Male radiated tortoises may also be known to use the force mating strategy wherein they use around vegetation to trap or even prevent females from getting away, then pin them straight down for copulation.

Turtles Courtship Shows

Red-eared sliders are an example of a fully marine species where the male works a courtship behavior. In this case the man extends his forelegs with all the palms facing out and flutters his forelegs within the female's face. Female options are important in this technique, as well as the females of several species, such as green sea turtles, aren't usually receptive. As such, they've progressed certain behaviors to avoid the male's attempts in copulation, such as swimming away, confronting the man followed by biting, or even a refusal position within which the female assumes a vertical position with her limbs widely outspread and her plastron dealing with the male. If the water is too superficial to perform the refusal position, the females will resort to beaching on their own, which is a proven deterrent method, as the particular males will never follow all of them ashore.

Ecology and life history of turtles

Ocean turtle swimming

Although numerous turtles spend large amounts of their lives marine, all turtles and tortoises breathe air and must surface at regular intervals to refill their lungs. They can also spend much or all of their lives on dried out land. Aquatic respiration in Australian freshwater turtles will be currently being studied. Several species have large cloacal cavities that are covered with many finger-like projections. These projections, called papillae, possess a rich blood provide and boost the surface area of the cloaca. The particular turtles can take upward dissolved oxygen from the particular water using these papillae, in much the same method that fish use gills to respire.

Like some other reptiles, turtles lay ovum that are slightly gentle and leathery. The eggs from the most significant species are spherical while the ovum of the rest are usually elongated. Their albumen is white and contains an alternative protein from bird ovum, such that it will not coagulate when cooked. Turtle eggs prepared to eat consist mainly of yolk. In some species, temp determines whether an ovum develops into a man or even a female: a higher temperature the female, a lower temperature the man. Large numbers of ovum are deposited in openings dug into mud or even sand. They are after that covered and left in order to incubate on their own. Depending upon the species, the ovum will typically take 70–120 days to hatch. Once the turtles hatch, they squirm their way to the surface and head against the water. You can find no known species where the mom cares for her young.

Sea turtles lay their eggs on dry, exotic beaches. Immature sea turtles are not cared regarding by the adults. Turtles can take many yrs to reach breeding age, plus in many cases, breed every few years rather than annually.

Researchers have lately discovered a turtle's internal organs usually do not slowly but surely break lower or become less efficient over time, unlike the majority of other animals. It has been found that the liver, lungs, and kidneys of a centenarian turtle are usually nearly indistinguishable from those of its immature version. This has inspired hereditary researchers to get started evaluating the turtle genome with regard to longevity genes.

A group of turtles is known as a bale.

Turtles Diet

A green ocean turtle grazing on

A turtle's diet varies greatly determined by the atmosphere by which it lives. Adult turtles typically eat aquatic plants; (citation needed) invertebrates like insects, snails, and worms; and have already been reported to occasionally eat dead marine animals. Several small freshwater species are carnivorous, eating small seafood and a variety of aquatic existence. However, protein is essential to turtle growth and juvenile turtles are purely carnivorous.

Sea turtles usually feed on jellyfish, sponges, and other soft-bodied organisms. Some species with stronger jaws have been noticed to eat shellfish, while others, including the green ocean turtle, do not consume meat at all plus, instead, possess a diet mainly made up of algae.

Systematics and evolution of Turtles

Primary article: Turtle classification

See|Observe|Notice} also: List of Testudines households

Life restoration of Odontochelys semitestacea, the oldest known turtle relative with a partial shell

"Chelonia" from Ernst Haeckel's Kunstformen der Natur, 1904

Centered on body fossils, the first proto-turtles are believed to have existed in the late Triassic Period of the Mesozoic era, about 220 million years ago, and their shell, which usually has remained a remarkably stable body plan, is thought to have evolved from bony extensions of their own backbones and broad steak that expanded and grew together to form the complete shell that offered protection at every stage of its evolution, even when the bony element of the shell was not complete. This is supported by fossils of the particular freshwater Odontochelys semitestacea or "half-shelled turtle with teeth", from the late Triassic, which have been found near Guangling in south west China. Odontochelys displays a complete bony plastron plus an incomplete carapace, comparable to an early stage of turtle embryonic advancement. Just before this discovery, the earliest-known fossil turtle ancestors, like Proganochelys, were terrestrial together a complete covering, offering no clue to the evolution of the exceptional anatomical feature. By the past due Jurassic, turtles had extended widely, and their fossil history becomes easier to go through.

Their exact ancestry offers been disputed. It has been believed they are the particular only surviving branch associated with the ancient evolutionary quality Anapsida, which includes groupings such as procolophonids, millerettids, protorothyrids, and pareiasaurs. All anapsid skulls lack a temporal opening while all some other extant amniotes have temporary openings (although in mammals, the hole has turn out to be the zygomatic arch). The particular millerettids, protorothyrids, and pareiasaurs became extinct in the particular late Permian period plus the procolophonoids during the Triassic.

However , it was later recommended that the anapsid-like turtle head might be due to reversion rather than to anapsid descent. More recent morphological phylogenetic studies with this particular in mind placed turtles firmly within diapsids, slightly closer to Squamata than to Archosauria.[55][56] All molecular studies have got strongly upheld the placement of turtles within diapsids; some place turtles within Archosauria, or, more commonly, as a sister team to extant archosaurs,[58][59][60][61] though an analysis carried out by Lyson et ing. (2012) recovered turtles because the sister group of lepidosaurs instead. Reanalysis of before phylogenies suggests that they classified turtles as anapsids both simply because they assumed this classification (most of them studying what sort of anapsid turtles are) and because they did not sample fossil and extant taxa broadly enough regarding constructing the cladogram. Testudines were suggested to get diverged from other diapsids between 200 and 279 mil years ago, though the particular debate is far through settled. Even the traditional placement of turtles outside Diapsida cannot be dominated out at this stage. A combined analysis of morphological and molecular data conducted by Lee (2001) found turtles to be anapsids (though a relationship with archosaurs couldn't end up being statistically rejected).[64] Similarly, a morphological research conducted by Lyson ainsi que al.. (2010) recovered them as anapsids most carefully related to Eunotosaurus. The molecular analysis of 248 nuclear genes from sixteen vertebrate taxa suggests that turtles are a sister group to birds and crocodiles (the Archosauria).[66] The date of separation of turtles and wild birds and crocodiles was approximated to be 255 mil in years past. The most latest common ancestor of living turtles, corresponding to the split between Pleurodira and Cryptodira, was estimated to get occurred around 157 million years ago. The oldest defined crown-group turtle (member of the modern clade Testudines) is the species Caribemys oxfordiensis through the late Jurassic period (Oxfordian stage). Through utilizing the very first genomic-scale phylogenetic analysis of ultraconserved elements (UCEs) to investigate the placement of turtles within reptiles, Crawford et al. (2012) also suggest that turtles are the sister group to wild birds and crocodiles (the Archosauria).

The first genome-wide phylogenetic analysis was completed simply by Wang et al. (2013). Using the draft genomes of Chelonia mydas plus Pelodiscus sinensis, the group used largest turtle information started date in their analysis and concluded that turtles are likely the sister group of crocodilians and birds (Archosauria). This particular placement within the diapsids suggests that the turtle lineage lost diapsid skull characteristics as it right now possesses an anapsid-like head.

The earliest known completely shelled member of the turtle lineage is the particular late Triassic Proganochelys. This particular genus already possessed several advanced turtle traits, and thus probably indicates several millions of years associated with preceding turtle evolution; this particular is further supported by evidence from fossil paths from the Early Triassic of the United States (Wyoming and Utah) plus from the Middle Triassic of Germany, indicating that will proto-turtles already existed as early as the Early Triassic. Proganochelys lacked the opportunity to pull its head into its shell, had a long neck, and had the long, spiked tail finishing in a club. While this body form is similar to that of ankylosaurs, this resulted from convergent advancement.

Turtles are divided directly into two extant suborders: Cryptodira and Pleurodira. The Cryptodira is the larger associated with the two groups plus includes all the ocean turtles, the terrestrial tortoises, and several of the freshwater turtles. The Pleurodira are sometimes known as the side-necked turtles, a guide to the way they retract their heads to their shells. This smaller group consists mainly of various freshwater turtles.